Added missing escape of $distinguishedName

Fix for http://sourceforge.net/apps/trac/adldap/ticket/42
Added function setBaseDn

Fix for http://sourceforge.net/apps/trac/adldap/ticket/44
Added function isGroup to determine if a distinguished name is a group
Obtain the group's distinguished name based on their groupid
Added function search
Removed isGroup and added getObjectClass to adLDAP
Fixed search function and added getObjectClass
Copy member;range=0-1499 to member to make the first 1500 results available
Added sn to search filter
Changed search filter to anr
Excluded computer accounts again
Added ad ldap range support for >1500 group members
array_keys($members[0])[0] is not supported in older php versions.
Merge pull request #2 from gitmopp/master

Fix for missing escape and minor enhancement